Stair-protractor.



C. W. REVEAL.

STAIR PROTRACTOR.

APPLICATION nun MAY29. 191s.

marzwh/fi ba ZvwmrroR A TTOENEJ' Patented Dec. 11, 1917.

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Be it known that I, CHARLEs W. REVEAL,

I "a citizenof the United States, residing at St'Joseph, in the county of Buchanan and State of Missouri, have invented certaln new and useful Improvements in Stair- Protractors, of which the following is a specification. y a

The presentinvention relatesto new and useful improvements in geometrical instruments, and has particular reference to new and useful improvements instair protractors and the like. i

The primary object of my invention is to provide a stair protractor having an improved structure and arrangement of parts whereby the same may be adapted for lay ing off various types of stair-ways, either for open or housed stairs. The device 'is also particularly adapted for use wherein a portion of the stair-way, that is, the outer edge is exposed to view, and the mner edge is flush with a wall or the like. My invention will be found particularly adapted for laying off wall and face strings in a manner which will hereinafter appear.

Other objects and advantages to be de rived from the use of my improved stair protractor will be seen from the following detail description and the claims, taken with an inspection of the accompanying drawings, in which:

Figure 1 is a plan view of a stair protractor embodying the improvements of my invention;

Fig. 2 is a side elevational view of the same; and

Fig. 3 is an enlarged fragmental sectional view of the detachable nose portion.

Referring more particularly to the drawings, wherein similar characters of reference designate like and corresponding parts throughout the various views, 1 designates the square of my improved protractor, the same being composed of the blades 2 and 3. The outer edges of the blades 2 and 3 are relatively at right angles. The inner edges are relatively at an acute angle whereby to form tapering blades.

The bladesQ and 3 are provided with scales in inches designated 4- and 5, said scales being arranged on the outer edges of the blades. The blades are also provided with longitudinally extending slots 6 and 7,

said slots terminating short of the ends of sra n-raornaoron. M f y 7 y m p Specification of L ette rs Patent. Application filedMay 29,1916. Serial No.100;541.

inventionincludes an angle-iren 8 having one of the portions thereof providedwith a pair ofllongitudinally extending alined slots 9 and 10,fasteningscrews and nuts 11 and 12 passing through the slots 6 a and 7 and said slots9and 10for retaining the arm 8 in theposition to which the same is moved. The arm 8 isalso provided with aplurality' of inwardly extending lugs 13, 14, 15, said lugs being arranged at the extrenie endsof the saidarm 8 andatthe intion. i a Y c I provide a removable nose designated 16, the inner marginal edge thereof bemg'pro- :vided with a reduced portion 1-7 formed with a longitudinally extending recess 18.

:termediate portion thereof; "said lugs servmg as stair engaging members for supporting the device during the laying off iopera- The reduced portion is in the form of a tongue and is receivable in a groove 19 formed in the outer marginal edge of the blade 2 and opening through the marginal edge of the adjacent blade. A plurality of pins 20 rigidly carried by the blade engage the'longitudinally extending recess 18 .and serves .to frictionally retain the nose '16 in position. 1

In use the diagonal arm 8 is set to the rise and tread of the steps. Therise and tread are determined definitely before attempting to lay off the steps, the scales 4 and 5 being employed for cooperation with the arm 8 to indicate in inches the rise and tread. The device is now placed upon the may be laid off on the plank or board. The

nose 16may be employed for giving the correct beading Or edge on the stair tread.

The nose also serves to give the proper cove. The inner edges of the blades serve to properly lay off the wedgeof the tread and rise in the event that a recess joint is to be made between the tread and rise at their inner edges.

If the stairs to be laid off are composed of a wall string and face string with a mitered riser then the nose 16 is removed. The facestring is then laid off working in the usual manner. It is unnecessary to state the'angle offt he diagonal bar 8 and therefore, it Will be seenthat accidental dis- 10 ;had, and WhileI have shown and described 1 my invention as embodying a specific structure I desire thatitbeunderstood that I may make suchchanges in said structure as do not depart from the spirit and scope of the invention as claimed.

\{Vhat I claim as new and desire to secure by Letters Patentis:

1. A stair protractor of the class described including rightangularly arranged blades, .saidblades being provided With slots, an .angle iron diagonal, guide arm arranged on said blades, one of the portions ofsaid arm .having'slots jtherein, fastening means excopies of this patent may be obtained tor tending through the slots in said arm and blades, and a plurality of lugs on said arm arranged at the extreme ends and intermeand ina single plane therewith for the purpose specified.

2. A stair protractor including a body composed of right angularly arranged blades, a diagonal guide arm arranged on said blades, the outer edge of one of said blades adjacent its jointure, having a longitudinally extending groove therein opening through the adjacent edge of the other blade, a nose having a reduced portion adapted to engage the said groove, said reduced portion having a longitudinally extending recess at one side thereof, and pins carried by the blade and engageable in said recess to frictionally retain the nose in position.

In testimony whereof, I aflix my signature hereto.

CHARLES WV. REVEAL.

five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

